HOW: Begin this exercise laying face down with your feet anchored onto the GHD with the pads on the top part of your thigh. From this position, assume a plank position keeping your body parallel with the floor and hold this position for the prescribed amount of time.
FEEL: You should feel the muscles in your back and hip working to hold the given position.
COMPENSATION: Avoiding arching at the back or allowing your chest to fall towards the floor.